These studies are designed to observe both central and peripheral reflex influences on renin control and blood pressure regulatory mechanisms. The effects of graded respiratory acidosis on renin and cardiovascular parameters are being observed. In addition, cardiopulmonary short-term reflex modulation of renin is being examined. Additional work is being conducted to study the influences of hypothalamic stimulation on cardiovascular and renin patterns in free-running dogs. BIBLIOGRAPHIC REFERENCES: Zehr, JE. Neurally mediated inhibition of renin disease. Part IV, Chapter I pp. 221-234, Regulation of Blood Pressure by the Central Nervous System (Onesti, ed.) Grune and Stratton, New York, N.Y. 1976. Zehr JE, Hasbargen JA and Kurz KD. Reflex suppression of renin secretion during distension of cardiopulmonary receptors in dogs. Circ Res 38 (4):232-239, 1976.